This patch stems from D84112.
New dwarf operator DW_OP_LLVM_implicit_pointer is introduced (present only in LLVM IR)
This is needed because representation and specification (types of operands) of it a bit different than actual dwarf expression DW_OP_LLVM_implicit_pointer. while creating actual DWARF info it will be converted to DW_OP_LLVM_implicit_pointer